Do older people become more cynical and distrusting of others as a result of their life experiences?

It's possible. Experiences can teach you a lot. But it shouldn't be the end all be all for what determines your decision making.

I can relate to feeling this way. I don't trust anyone or expect anything from anyone.

However, that doesn't mean I wouldn't accept help from people or just completely cut everyone off. I take everything on a case by case scenario. Nobody's perfect and life tends to put us all through the ringer at some point young or old.